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Nat 5 Cells
Nat 5 Membranes and Mitosis
Question | Answer |
---|---|
What happens to animal cells when they are placed in pure water? | Water moves into them by osmosis, they swell up and eventually BURST (lyse). |
What happens to plant or fungal cells when they are placed in pure water? | Water moves into them by osmosis, their vacuole swells up, and they become TURGID. |
What happens to animal cell when placed in solution containing lower concentration of water than they contain? | Water leaves the cell by osmosis, cell shrivels and becomes CRENATED. |
What happens to plant cell when placed in solution containing lower concentration of water than they contain? | Water leaves the cell by osmosis, cytoplasm pulls away from cell wall and cell becomes PLASMOLYSED |
What happens to a cell placed in solution which has the same concentration of water as the cell? | There is no water movement, cell remains the same weight and size. |
What happens to the mass (weight) of the cell If the water is leaving the cell by osmosis? | The mass (weight) reduces |
What happens to the mass (weight) of the cell If the water is entering the cell by osmosis? | The mass (weight) increases |
What are the two main components of a cell membrane? | phospholipid and protein |
What is osmosis? | Movement of water through a selectively permeable membrane from high to low concentration of water. |
What is a selectively permeable membrane? | Membrane that allows small molecules to pass but does not allow large molecules to pass |
Examples of small molecules that can pass through a selectively permeable membrane are? | water, alcohol, simple sugars (eg. glucose), |
Examples of large molecules that can not pass through a selectively permeable membrane are? | DNA, proteins, fats, starch |
What is the percentage water in a 70% ethanol solution? | 70% ethanol solution contains 30% water. |
Which solution has higher water concentration, 20% salt or 10% salt solution? | 10% salt solution has higher water concentration |
In what way do molecules move by diffusion? | From high concentration to low concentration, down a concentration gradient. |
In what way do molecules move by osmosis? | From high concentration to low concentration, through a selectively permiable membrane, down a concentration gradient |
In what way do molecules move by active transport? | From low concentration to high concentration, through a selectively permiable membrane, up (or against) a concentration gradient. |
What is active transport? | The movement of molecules from a region of low concentration to a region of high concentration against a concentration gradient |
Do diffusion and osmosis require energy? | No, moving molecules down a concentration gradient does not require energy. |
Does active transport require energy? | Yes, moving molecules against a concentration gradient does require energy. |
What is the name for types of transport not requiring energy? | Passive transport |
What is mitosis? | Mitosis is a process of cell division in which a cell divides into two identical daughter cells, each containing the same number of chromosomes as the starting cell. |
Why is it important that every new cell has exactly the same number of chromosomes as the original cell? | It is important that every new cell has exactly the same number of chromosomes as the original so that no genetic information is lost. |
What happens in stage 1 of mitosis? | Chromosomes in the nucleus coil up, replicate and become visible on staining. |
What happens in stage 2 of mitosis? | Chromosomes now consist of two identical Chromatids joined by a Centromere |
What happens in stage 3 of mitosis? | Chromosomes line up along the middle of the cell and spindle fibres attach to chromatids. Nuclear membrane disappears. |
What happens in stage 4 of mitosis? | Spindle fibres pull chromatids towards opposite ends (poles) of the cell. |
What happens in stage 5 of mitosis? | Nuclear membranes reform. Cytoplasm divides. |
What happens in stage 6 of mitosis? | At stage 6 there are 2 diploid daughter cells containing the same number of chromosomes as the original cell. These are identical to each other and to the original cell. |
What part of the cell controls cell division? | The nucleus controlls cell division |
What is the name for cells with a full set of chromosome pairs? | A diploid cell |
Why do cells need to divide? | In unicellular organisms for reproduction. In multicellular organisms for growth and repair. |